textproduct: Rapid City

KEY MESSAGES

- An active pattern will bring unsettled conditions at least through the weekend, with daily chances for thunderstorms.

- Temperatures will generally be near average through the end of the week into early next week.

UPDATE

Issued at 950 PM MDT Thu Aug 13 2026

03Z surface analysis shows troughing over southeastern MT this evening, another disturbance behind it over Idaho with a frontal boundary snaking into Wyoming and Colorado. Radar shows showers over eastern Wyoming and southeastern MT moving northeast synoptically with the disturbance. Precipitation will remain in the overnight hours as the wave slides eastward.

Very little change to the overall forecast this evening. Have made some minor tweaks to PoPs and QPF over the next 24 hours as hi-res models update and based off current observations. Patchy areas of fog may occur overnight given the moist air and light winds. Another disturbance still progged to move through the area tomorrow, continuing the trend of scattered showers over the area. Severe weather is not expected.

DISCUSSION

(This Evening Through Thursday) Issued at 208 PM MDT Thu Aug 13 2026

Water vapor imagery shows broad upper ridging centered across south SE CONUS with the main axis stretching through the Midwest. Moist, active southwesterly flow continues across the western CONUS...all the way back to a trough near the West Coast. Several shortwaves are crossing northern High Plains to the central/northern Rockies. The nearest wave is pushing through central/eastern WY through the NE WY zones south into the CYS CWA. As the wave continues NE, showers and thunderstorms will push further into western SD while weakening. Weak CAPE and shear will damper any severe weather potential today. The next (much stronger) wave will bring continued chances of elevated convection late this evening and into the overnight hours. These showers could generally produce up to half an inch of QPF by 12z. Active weather will continue through Friday with additional shortwaves bringing mid-level forcing. Models show a surface low strengthening tomorrow near the ND/MT line with a cold front pushing through NE WY and far western SD. Good Theta E advection across NW/Central SD ahead of the front will support SBCAPE nearing 2000 J/kg. While shear is not impressive, could still see pulsing isolated strong/severe storms Friday afternoon and early evening, with large hail as the main threat. Active weather and near average temperatures will continue through weekend into the first half of next week, with daily chances for showers and thunderstorms.

AVIATION

(For the 06Z TAFS Through 06Z Friday Night) Issued At 1001 PM MDT Thu Aug 13 2026

Scattered showers will be possible across the forecast area overnight. MVFR to IFR conditions are expected tonight across the area as moist southeast upslope flow continues. Fog may develop overnight across the Black Hills and areas south of I-90 before burning off Friday morning.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.